Vehicle emissions control systems may be configured to store fuel vapors from fuel tank refueling and diurnal engine operations, and then purge the stored vapors during a subsequent engine operation. In an effort to meet stringent emissions regulations, emissions control systems may need to be intermittently diagnosed for the presence of leaks that could release fuel vapors to the atmosphere.
Some leak test methods include evacuating the emissions control system and testing whether the vacuum level is maintained, while other methods include pressurizing the emissions control system and determining whether the pressure level remains steady. Some of these known leak test methods can pinpoint the location of leaks in addition to detecting the existence of a leak.
However, the methods described above are typically limited to locating leaks in particular components of the emissions control system, such as valves. In some instances, leaks may occur in the vapor lines which couple the components of the emissions control system. For example, vapor lines typically include “quick connect” (QC) interfaces which easily snap together and lock in place, thereby improving serviceability of the emissions control system. If the quick connect interfaces are not properly snapped in and locked, or are snapped in and not locked, then leaks will occur. In the presence of such leaks, known diagnostics methods only indicate the existence of a leak, and are incapable of indicating the location of the leak.
When a diagnostic light comes on responsive to a failed leak test, the driver brings the vehicle to an automotive repair garage. There, in order to determine the location of the leak, a technician or mechanic may perform a smoke test with a smoke test apparatus. The smoke test apparatus generates smoke which fills the emissions control system and leaks out of the leak. The technician then identifies the location of the leak by observing the smoke exiting the leak. In the case of an improperly secured quick connect causing the leak, the technician can then properly snap in and lock the quick connect to stop the leak.
While smoke tests are effective, they are also intrusive to the emissions control system, time consuming, and expensive. Furthermore, if the leak is caused by an improperly secured quick connect, a smoke test may be an unsuitable approach.
In one example, the issues described above may be addressed by a method comprising monitoring an equivalent resistance of a leak detection circuit, and indicating a leak responsive to the equivalent resistance not equal to a threshold resistance. In this way, leaks in vapor line interfaces can be easily detected and located without intrusively testing the emissions control system.
In another example, a connector assembly comprises: a first connector comprising a housing defining a protruded portion and a first interface; a second connector comprising a housing defining a cavity and a second interface, the second connector matable with the first connector wherein the cavity receives the protruded portion and the first interface contacts the second interface; an electrical force-sensing element positioned on and substantially covering one of the first interface and the second interface; and an electrical resistor integrally formed in the housing and electrically coupled in series to electrical ground and to the electrical force-sensing element. In this way, the connector assembly, when used to connect vapor lines to components of an emissions control system, can provide a unique signal to indicate whether the connector is securely fastened.
In yet another example, an evaporative emissions system comprises at least two quick-connect interfaces configured to couple together elements of the evaporative emissions system, each quick-connect interface comprising a force-sensing element configured to output a unique signal upon forming a seal. In this way, particular connections with leaks may be detected and fixed, thereby reducing emissions.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.